Autopsies are messy affairs, especially when performed on the remains of a deceased presidential campaign. Take the Romney campaign, to pick a recently interred, but still fresh, cadaver.

The examination in the Romney case involving a search for the cause of death is in the hands of the longest list of Republican coroners since Tom Dewey lost an earlier sure-thing election in 1948 to Harry Truman, another Democratic president despised and discounted by the GOP.

Every Republican who used to be anybody is on this case — Newt Gingrich, Rush Limbaugh, Peggy Noonan, Paul Ryan and Mitt Romney himself, an assortment of red-faced Republican-leaning political pundits and those peddlers of fictitious political forensics at Fox News and the Wall Street Journal editorial pages.

The reasons they’ve found for Romney’s demise are many and varied — Democrats’ success in branding Romney an out-of-touch job exporter, Hispanics teed off by his anti-immigrant rhetoric, young women appalled by rape’s-not-such-a-big-deal comments by a pair of tea party Senate candidates. And besides, Romney was a lousy candidate.

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Much of that’s true. Romney was a klutz as a candidate. But he didn’t bring down the Republican Party so much as it brought him down. The cliché about the Grand Old Patricians is true: They’re a 20th-century party in a 21st-century country.

Here’s an example. Apologists for the party contend that to get back its groove, the GOP needn’t rethink its principles — merely tinker with its policies, especially immigration. Takes a while to get your mind around that one because policies are usually thought of as the product of principle: If one is flawed, the other’s bound to be. But let’s look at Republican principles.

None is more sacred to the Grand Old Patricians than the rule that says, “Thou shalt not raise taxes, ever” especially on those best able to pay them — the wealthy, millionaire division in particular. It’s the pole star of GOP principle.

As everyone knows, God created the GOP to oppose taxes. And Grover Norquist (he of the “no tax” pledge) is God’s prophet here on Earth, making make sure the party never forgets. (Why do you think the elephant is the party symbol?)

Remember that early GOP primary debate when the entire field of candidates was asked if they’d accept $1 in tax increases for every $10 in spending cuts? It was a deal of a lifetime. But, in an appalling display of collective cowardice, every candidate — bar none — signaled “no way.” Romney among them. They caved in to Grover and the tea party.

One can only wonder why a party seeking the votes of ordinary Americans would go out of its way to protect a privileged class already enjoying preferential tax rates on interest, dividends and capital gains unavailable to most people living only on earned incomes. Hedge fund income, for example, is taxed not as regular earned income, but at the 15 percent capital gains rate. We should all be so lucky.

Corporations, of course, do equally well. Oil giants such as Exxon Mobil, among the wealthiest organizations in history, actually draw subsidies (e.g., oil depletions allowances) from the federal government — another term for you and me. And let’s not even mention those bailed-out belly-achers, the big banks.

A corollary to the GOP’s “no tax” fixation is the belief that 1) we spend too much, and 2) the federal tax take is too large. They’re right about the first; we do spend too much. But they’re dead wrong about the second.

If you can believe the economists (too many are “on-the-one-hand, but-on-the-other-hand” people), federal taxes as a percent of gross domestic product are the lowest in roughly half a century — about 16 percent, by one count, well below the 21 percent average.

Romney’s taking a beating now from finger-pointing sore losers in the GOP. But, in truth, much of the real blame for his loss lies with the Republican Party itself. Its brand has gone sour, in large part because its tax policy in defense of the rich has become toxic.

Moreover, it’s about to lose the tax fight in any case. Within the next year, federal taxes will be raised. The only questions are which taxes and/or loopholes will be affected, when and by how much.